The invention relates generally to the separation of gas mixtures by pressure swing adsorption and relates more particularly to the process steps involved in pressure swing adsorption and systems utilized for carrying out such steps.
The type of pressure swing adsorption system with which this invention is concerned includes one adsorber having a fixed bed of adsorbent material and a reservoir. The adsorber includes an inlet and an outlet accommodating a flow of gas through the adsorbent material, and the adsorbent material is adapted to fractionate at least one constituent from a gaseous mixture, or feed stream, fed into the adsorber inlet so that product gas exits the adsorber outlet. The reservoir is connected in flow communication with the adsorber outlet for receiving the product gas exiting the adsorber.
It is known that operation of the afore described system can be carried out in cycles wherein each cycle includes a series of process steps. For example, the first of such steps may involve a production stage wherein a gaseous feed stream is directed into the adsorber inlet and product gas produced by the adsorber is collected in the reservoir. The feed stream flow and the flow of product gas between the adsorber and the reservoir are subsequently shut off, and the adsorber inlet is vented to the atmosphere in a desorption stage. The feed stream flow into the adsorber and the product gas flow between the adsorber and the reservoir are thereafter resumed. During the initial moments of feed stream resumption, product gas flows from the reservoir to the adsorber as the internal pressure levels of the adsorber and reservoir move toward equalization. The feed stream continues to be delivered into the adsorber inlet so that upon equalization of the adsorber and reservoir pressures, the process cycle begins again with a production stage. The aforedescribed process steps of the operation may be controlled with valves connected upstream and downstream of the adsorber and suitable timing mechanisms and control switches associated with the valves. An example of a prior art system of the aforedescribed type is shown and described in U.S. Pat. No. 4,561,865.
It is an object of the present invention to provide a new and improved pressure swing adsorption process utilizing a single adsorber and a system for performing such a process.
Another object of the present invention is to provide such a process and system wherein the production of product gas by the process and system is enhanced.
Yet another object of the present invention is to provide such a process and system which is particularly well-suited for providing a product stream of relatively high purity oxygen from air.
A further object of the present invention is to provide such a system which is uncomplicated in construction and effective in operation.